The invention relates to a locking device for the releasable locking of one component relative to another in one of a plurality of possible relative positions, in particular for a crash-active head restraint of a vehicle.
Such a locking may be carried out in the prior art by a toothed portion into which a bolt positively engages at various positions. Such bolts are generally tensioned by spring force in the direction of the toothed portion. During adjustment, the bolt may be lifted counter to the spring force, so that the locking is released and an adjustment of the relative position may take place. Optionally, the adjustment may also be undertaken without lifting the bolt, provided the inclination of the tooth flanks is correspondingly flat. Moreover, the bolt and toothed portion may be designed to be asymmetrical such that an adjustment in one direction is also possible when the bolt is not released, whilst an adjustment in the opposite direction requires a release of the bolt. In particular (but not only) in the last-mentioned locking devices a rattling noise may be produced during adjustment without prior release of the bolt, which has a troublesome effect. Moreover, as a result, increased wear may occur on the bolt and toothed portion. A head restraint is further disclosed in the publication DE 199 23 909 A1, which consists of a base body connected rigidly to the backrest of the vehicle seat via retaining bars, optionally also in a height-adjustable manner, which is arranged in a padded segment formed in the manner of a trough. In the event of an accident, the padded segment is moved in a translatory manner toward the head of the seat occupant in order to prevent whiplash injury. The force required therefor is produced by a spring pretensioned in the direction of displacement within a telescopic guide device. Head restraints are further disclosed in the publications DE 10 2004 016 474 B3, DE 103 48 939 B3 and DE 10 2005 052 766 B3.